Conveyor chain is used in conveyor systems in many industries including, but not limited to food processing, packaging, canning, bottling and warehouse product transfer. Typically, metal conveyor chain is used to move a particular product along a conveyor path.
It is known to provide a conveyor chain 10 as shown in FIGS. 1 and 2 which illustrates a portion of the conveyor chain 10 including two roller links 20 coupled by a connecting link 30. In FIGS. 1 and 2, components are shown with exaggerated spacing therebetween for illustration purposes. Each of the roller links 20 include two rollers 21 having an exterior surface 22 for supporting the product to be conveyed and an interior surface 23. Each roller link 20 includes two chain pins 24 having exterior surfaces 25 and chain pin bores 26 extending therethrough. Two chain pins 24 are disposed between parallel facing chain plates 27. In particular, the exterior surfaces 25 of the chain pins 24 engage respective chain plate bores 28 formed in the chain plates 27. One of the rollers 21 is mounted for rotation on each of the chain pins 24 such that the interior surface 23 and the exterior surface 25 slidingly engage one another. The roller links 20 are pivotally coupled to one another by the connecting link 30. In particular, the connecting link 30 includes a link pin 31 having a link pin exterior surface 32 and a pair of parallel facing link plates 33 each having two link pin bores 34 disposed therein. The parallel facing link plates 33 are positioned on opposing sides 29A and 29B of the roller link 20 such that chain plate bores 28 are coaxial with respective link pin bores 34. The link pin 31 extends through the chain pin bore 26 and the chain plate bore 34. Opposing ends of the link pins 31 are coupled to the parallel facing link plates 33 by engagement of the link pin exterior surface 32 with the chain pin bore 26.
It is known to provide a lubricant such as grease or oil between the interior surface 23 and the exterior surface 25 and between the link pin exterior surface 32 and the chain pin bore 26 to reduce wear. It is also known to use bushings manufactured from bronze, polytetrafluoroethylene (PTFE) and lead between sliding components in an effort to reduce friction.
Lubrication of chain components with lubricants such as grease and oil can increase maintenance costs and cause contamination of the products being conveyed. In addition, control and disposal of lubricants involve complex and costly procedures derived from environmental laws. Therefore, there has been a growing demand to reduce or eliminate the use of lubricants such as grease and oil in chain conveyors.
Use of bronze, PTFE and lead bushings in chain conveyors has been problematic because they result in reduced load carrying capability, reduced chain life, and limited material compatibility. Thus, there is a need to provide a bearing for chain conveyors that minimizes the need for periodic lubrication and withstands high conveyor loads.